Coming home from a relaxing vacation should feel amazing, but sometimes you open your front door and get hit with a smell that makes you wonder if something died in your house while you were gone. You cleaned out the fridge, took out all the trash, and left everything spotless before you left. So where is that awful odor coming from? If you follow your nose to the kitchen or bathroom sink, you’ve found your culprit. The good news is that this stinky situation is incredibly easy to prevent with just a glass of water, a paper towel, and about 30 seconds of your time before heading out the door.
Your drain trap dries out when you’re away
Every sink in your home has a clever piece of plumbing called a P-trap, which is that curved pipe underneath your sink that looks like the letter P or U turned on its side. This simple curve holds a small amount of water that creates a seal between your home and the sewer system. When water sits in that curve, it blocks nasty sewer gases from backing up through your pipes and entering your house. It’s a brilliant design that works automatically every time you use your sink, requiring no moving parts or special maintenance.
The problem starts when you stop using that sink for an extended period. While you’re away enjoying your vacation, the water in that P-trap slowly evaporates into the air. Depending on your climate and the time of year, this process usually takes about a month under normal circumstances. But if you have a sink that wasn’t used much before you left, like a guest bathroom or that utility sink in the basement, the trap might already be half-empty when you walk out the door. That means even a week-long trip could be enough time for it to dry out completely and allow those gross sewer smells to creep into your home.
The paper towel and glass trick is surprisingly effective
This simple hack works by tackling the evaporation problem from multiple angles at once. Before you leave for your trip, fill a glass with cold water and pour it down the drain to make sure that P-trap is completely full. Then take a paper towel, dampen it with water, and lay it flat across the drain opening. The wet paper towel acts as a temporary seal that slows down the evaporation process significantly. Finally, place the empty glass upside down on top of the paper towel to hold it in place and provide an extra barrier against air flow.
This three-part system addresses every aspect of the dry trap problem. The initial glass of water ensures you’re starting with a full trap, the damp paper towel creates a moisture barrier that slows evaporation, and the glass keeps everything in place while also preventing the paper towel from drying out too quickly. Some people prefer to fill the glass with water before flipping it upside down onto the paper towel, which adds even more moisture to the seal. Either method works well, though using extra absorbent paper towels might give you better results if you’re going to be away for more than a week or two.
Winter and dry climates speed up the process
If you live in an area with low humidity or you’re traveling during the winter months, your P-trap can dry out much faster than that typical one-month timeframe. Winter air tends to be extremely dry, especially inside heated homes where the furnace constantly removes moisture from the air. This means the water in your drain trap evaporates more quickly, potentially leaving you with sewer gas problems after just a week or two away. Desert climates and other naturally dry regions face this same accelerated evaporation issue year-round.
Homes with older plumbing systems that use S-traps instead of P-traps are even more vulnerable to this problem. S-traps were common in older construction but are now banned by most building codes because the physics of their shape causes them to empty out more easily. If you have an older home and notice frequent drain odors, this might be why. The paper towel and glass trick becomes even more important in these situations, and you might want to use it even for shorter weekend trips if you know your drains are prone to drying out quickly.
Guest bathrooms and unused drains need extra attention
That spare bathroom you set up for guests who rarely visit is probably the biggest culprit for surprise sewer smells. These infrequently used spaces can sit for weeks or months without anyone turning on the tap, which means the P-trap is already well on its way to drying out before you even think about leaving for vacation. The same goes for floor drains in basements, laundry rooms, or utility areas that might only see water when you’re doing specific tasks or dealing with overflow situations.
Make a habit of checking these forgotten drains before any trip, no matter how short. Pour some water down each one and apply the paper towel and glass trick to any drain you haven’t used in the past week or two. This includes shower drains in guest bathrooms, that weird floor drain in the corner of your basement, and even the drain in your rarely used wet bar. Taking five extra minutes to address all these potential problem spots can save you from coming home to a house that smells like a sewer. You might want to set a reminder on your phone to run water through these drains once a month, even when you’re not traveling, just to keep the traps full and functional.
This trick also keeps bugs from entering your home
Here’s an unexpected bonus benefit that makes this hack even more valuable than just preventing bad smells. When your P-trap dries out, it doesn’t just let sewer gases into your home. It also creates an open pathway for insects and other pests to crawl up through your drain pipes and emerge right in your sink. Cockroaches, drain flies, and other creepy crawlies love exploring plumbing systems, and a dried-out trap is basically an engraved invitation for them to check out your house while you’re away.
By covering your drain with a damp paper towel and a glass, you create a physical barrier that these pests can’t easily cross. Any bugs that do try to make the journey will either die in the trap itself or get trapped under the glass where you can easily dispose of them when you get home. Sure, finding a few dead bugs in your sink isn’t exactly pleasant, but it beats discovering them scattered throughout your kitchen or bathroom after they’ve had free rein of your home for a week. This pest-blocking benefit makes the paper towel trick worth doing even if you’re only leaving for a long weekend.
Add mineral oil for extra long trips
If you’re planning to be away for more than a couple of weeks, or if you know your drains are particularly prone to drying out, you can add an extra layer of protection with a small amount of food-grade mineral oil. After pouring water down the drain to fill the P-trap, add about a teaspoon of mineral oil. The oil floats on top of the water and creates a thin film that significantly slows down evaporation. This works because water molecules have a much harder time escaping into the air when they have to pass through an oil barrier first.
You can find food-grade mineral oil at most drugstores or in the laxative section of grocery stores, though any mineral oil will work for this purpose. Don’t use cooking oils like vegetable or olive oil because these can go rancid and create their own unpleasant smells over time. After adding the mineral oil, still use the damp paper towel and glass trick on top for maximum protection. This combination can keep your P-trap sealed for months if necessary, making it perfect for extended travel, seasonal homes, or properties that sit vacant for long periods between uses.
Clean your drains before leaving for best results
While preventing your P-trap from drying out stops sewer gases from entering your home, it doesn’t address smells that might be coming from buildup and bacteria already living in your pipes. Before you leave for vacation, especially if it’s been a while since you’ve given your drains a good cleaning, take a few minutes to flush them out. Pour one cup of baking soda down the drain and let it sit for about 15 minutes. Then add half a cup of vinegar and wait another 15 minutes while the mixture bubbles and fizzes its way through any gunk stuck to your pipes.
After the fizzing stops, flush everything down with plenty of hot water to wash away the loosened debris and bacteria. This process cuts through the biofilm and residue that can create odors on its own, even when your P-trap is functioning perfectly. If you have a garbage disposal, use a long brush to scrub around the drain opening with warm soapy water before doing the baking soda and vinegar treatment. Then run cold water through the disposal for a minute to clear everything out. Combining this deep cleaning with the paper towel and glass trick ensures you’ll come home to drains that smell completely fresh.
Run water immediately when you return home
When you walk through your door after vacation, one of your first tasks should be removing those glasses and paper towels from your drains and running water through each sink for at least a minute. This flushes out any stagnant water that’s been sitting in the pipes and refills the P-trap with fresh water. Even if your prevention methods worked perfectly and there’s no smell, this quick flush helps restore your plumbing to normal working condition and clears out any debris or residue that might have settled in the pipes while you were gone.
Make this part of your post-vacation routine along with checking your mail and adjusting the thermostat. Walk through your house and run water in every sink, shower, and tub for 30 to 60 seconds each. This is especially important for those infrequently used fixtures in guest bathrooms and utility areas. If you do notice any lingering odors despite using the paper towel trick, don’t panic. Just run the water for a few extra minutes and the smell should dissipate as fresh water refills the trap and pushes out any gases that managed to sneak through. In most cases, everything will be back to normal within a few minutes of running water through your drains again.
Make this part of your pre-travel checklist
You probably already have a mental checklist of things to do before leaving for vacation. Lock the doors, set the thermostat, stop the mail, unplug unnecessary appliances, take out the trash, and clean out anything perishable from the fridge. Adding the glass and paper towel trick to this routine takes almost no extra time but can save you from an unpleasant surprise when you return. Keep a stack of paper towels in an easily accessible spot and make it a habit to work your way through the house doing each drain before you load up the car.
Some people find it helpful to create an actual written checklist that they keep on their phone or taped inside a kitchen cabinet. That way you’re not trying to remember everything in the chaos of getting out the door, especially when you’re running late or wrangling kids and luggage. Include all your drains on this list so you don’t accidentally forget that basement utility sink or the guest bathroom down the hall. Once this becomes part of your standard routine, it’ll take less than five minutes to protect all the drains in your entire house. That’s a pretty small investment of time for the peace of mind knowing you won’t be greeted by awful smells when you walk back through your door.
The glass and paper towel trick is one of those brilliantly simple solutions that seems almost too easy to work, but it really does prevent the stinky sewer gas problem that plagues so many homes after vacations. By taking just a few minutes before you leave to pour water down your drains, cover them with damp paper towels, and place glasses on top, you ensure the water in your P-traps stays where it belongs. Remember to pay special attention to those rarely used drains, consider adding mineral oil for longer trips, and make this hack a standard part of your travel preparation routine.
